:Glottal stop:

Pronunciation GB: ˈɡlɒtl, GA: ˈɡlɑt̬l

A consonant articulation symbolised ʔ and sometimes called a glottal plosive. Tight closure of the vocal folds interrupts the pulmonic egressive airstream and this causes an increase in pressure below the closure. When the vocal folds part, the compressed air is released.